Device for correcting the deflection of a large wide endless belt

ABSTRACT

An endless belt is trained over at least a pair of rollers, including at least one driven roller, and one of the other rollers is mounted for swinging about a pivot axis perpendicular to its axis of rotation. A pair of belt deflection detecting rollers are rotatably mounted adjacent respective opposite side edges of the belt and are spaced apart a distance slightly greater than the width of the belt so as normally to be out of engagement with the adjacent belt side edge. The detecting rollers are operatably connected to the mounting means for the swingable roller and are operable, responsive to rotation of the detecting roller by engagement with a belt side edge as a result of belt deflection, to swing the swingable roller about the pivot axis thereof in a direction to correct belt deflection.

United States Patent n91 Fujimoto Feb. 6, 1973 [54] DEVICE FORCORRECTING THE FOREIGN PATENTS OR APPLICATIONS DEFLECTION OF A LARGEWIDE 773 84 957 G B ..l98 02 E LESS BELT 8 5/ l reat main [2 [75]Inventor: Sakae Fujimoto, Chofu-shi, Tokyo, Primary Examiner-:Edward A.Sroka Japan I Attorney-McGlew and Toren [73] Ass1gnee: .llizlgshiklKaisha Rlcoh, Tokyo, ABSTRACT [22] Filed: 8 1970 An endless belt istrained over at least a pair of rollers,

App]. No.: 96,078

including at least one driven roller, and one of the other rollers ismounted for swinging about a pivot axis perpendicular to its axis ofrotation. A pair of belt deflection detecting rollers are rotatablymounted adjacent respective opposite side edges of the belt and arespaced apart a distance slightly greater than the width of the belt soas normally to be out of engage ment with the adjacent belt side edge.The detecting rollers are operatably connected to the mounting means forthe swingable roller and are operable, responsive to rotation of thedetecting roller by engagement with a belt side edge as a result of beltdeflection, to swing the swingable roller about the pivot axis thereofin a direction to correct belt deflection.

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SAKAE Fuzra Mo'l'o DEVICE FOR CORRECTING THE DEFLECTION OF A LARGE WIDEENDLESS BELT BACKGROUND OF THE INVENTION The provision of flanges onrollers having an endless belt trained thereover may be effective toprevent deflection of a relatively narrow endless belt from its normalpath of movement between rollers. However, in the case of a very wideendless belt, the force with which the belt is deviated to either sidefrom its normal path of movement is so large that it is not possible toprevent deflection of such a very wide endless belt by providing flangeson the belt rollers. Additionally, the provision of such flanges isdisadvantageous in that the side edges of the belt and the flanges rubagainst each other, thereby damaging the side edges of the belt. As aconsequence, it is not desirable to use devices relying on flangesrubbing against the side edges of an endless belt as a means forpreventing deflection of very wide endless belts from the normal path ofmovement between rollers.

It has been proposed to prevent deflection of a very wide endless beltby a device of the type shown in FIG. 1. As shown in FIG. 1, a very wideendless belt 101 is trained about two belt rollers 102 and 103, withroller 102 being so supported that it can be swung about its centralportion which serves as a pivot, when the belt is deflected to eitherside from its normal path of movement. Roller 103, which is mounted on ashaft 105a having a gear 104 secured to an end thereof, is adapted to berotated in the direction of the arrow a through the medium of gear 104and by a suitable drive means which has not been shown in FIG. 1. Ifbelt 101, moving in the direction of arrow b as roller 103 rotates, isdeviated in the direction of the arrow c, belt roller 102 will be swungin the direction of arrow d until it reaches a dash-and-dot lineposition 102A, at which point the very wide endless belt 101 will beginto shift in a direction opposite to the direction of arrow so that thedeflection of the belt is corrected.

It is well known that, when a very wide endless belt is deviated in onedirection, the deviation can be corrected by swinging one of the beltrollers in a direction in which the belt is to be shifted, as mentionedabove. It has hitherto been customary to provide a movable member (notshown) which is disposed on one side of endless belt 101 and adapted tobe forcibly moved when belt 101 deviates from its normal path ofmovement so as to swing belt roller 102. The movement of the movablemember is transmitted to roller 102 through a linkage or the like, sothat the device requires an undesirable multiplicity of parts and iscomplex in construction. In addition, the pressure applied to the sideedges of the belt is rather high, and consequently the belt is liable tobe damaged.

In place of using a complicated linkage, it has been proposed to useelectric means to detect the deviation of a belt and to cause one of thebelt rollers to be swung, responsive to a signal produced by thedetection means, so as thereby to move the belt back to its normal pathof movement. However, such an electric device is not withoutdisadvantages. The electric detection means must act with very highprecision and accuracy, and such a means is expensive to manufactureresulting in an increase in cost. Moreover, the connection of such anelectric detection means with mechanical means for actually swinging thebelt roller requires ingenuity and skill, and makes theconstructioncomplex.

SUMMARY OF THE INVENTION This invention relates to means for correctingautomatically the deflection of a very wide endless belt from its normalpath of movement and, more particularly, to an improved, simplified, andmore efficient belt deflection correction device particularly usablewith very wide endless belts such as used in a copying machine or in asheet conveying apparatus.

The objective of the invention is to provide such a belt deflectioncorrection device, for a very wide endless belt trained over at least apair of rollers, which obviates the disadvantages of all belt deflectioncorrection devices known hitherto.

In accordance with the invention, a pair of detection rollers aremounted for relatively free rotation adjacent opposite side edges of avery wide endless belt and in positions spaced slightly from theadjacent belt side edge. The detection rollers function in a manner suchthat, when the belt is deflected in one direction, the side edge facingin the direction of the deflection, rotates the adjacent detectionroller, and rotation of the detection roller is converted into swingingmovement of one of the rollers over which the endless belt is trained.

The resistance of the deflection detection rollers to rotation can beminimized by using, me means for swinging the belt roller, a threadedrod,having a small pitch as a member for moving a swingable belt rollersupporting member. This is conducive to eliminating the chance ofdamaging the edges of the belt brought into engagement with thedetection rollers to rotate the latter. The arrangement, in which thedetection roller driven by one of the belt side edges upon deviation ofthe belt from its normal path of movement directly swings one of thebelt rollers, makes the invention device simple in construction and [lowin cost.

However, the invention also contemplates other driving connectionsbetween the belt detecting rollers and the swingable mounting meanssupporting one of the belt rollers. Thus, for example, a movable cammember may be included in the driving means orv cams projecting radiallyfrom a detecting roller can be used as the drivingmeans. In the lattercase, suitable brake means are provided to limit the rotation of thedetecting roller then being driven by a side edge of the belt.

An object of the invention is to provide an improved and simplified beltdeflection correction device for a very wide endless belt trained overat least a pair of rollers.

Another object of the invention is to provide such a correction deviceincluding means mounting one of the belt rollers for swinging about apivot axis perpendicular to its axis of rotation.

A further object of the invention is to provide such a correction deviceincluding a pair of belt deflection detecting rollers rotatably mountedadjacent opposite side edges of the belt but normally out of engagementwith the adjacent side edges of the: belt.

Another object of the invention is to provide such a correction deviceincluding means operatively connecting the detecting rollers to themounting means and operable, responsive to rotation of a detectingroller by engagement with a belt side edge as a result of beltdeflection, to swing one roller about the pivot axis in a direction tocorrect the belt deflection.

For an understanding of the principles of the invention, reference ismade to the following description of typical embodiments thereof asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective viewillustrating the relative positions, in operation, of a swingable beltroller and an endless belt trained thereabout and about a fixedlypositioned belt roller;

FIG. 2 is a somewhat schematic plan view, partly broken away, of a beltdeflection correction deviceembodying the invention;

. FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a sectional view, on an enlarged scale, taken along the lineIV-IV of FIG. 2;

FIG. 5 is a perspective view, partly broken away, of the device shown inFIG. 2 with the base plate being omitted;

FIG. 6 is a plan view of another embodiment of the correction device inwhich a linkage is used in place of the transmission belt shown in FIG.2;

FIG. 7 is a front elevation view, partly in section, of the device shownin FIG. 6;

FIG. 8 is a plan view of another embodiment of the correction device inwhich the rotation transmission mechanism uses a linkage;

FIG. 9 is a perspective view of a portion of the mechanism of FIG. 8',

FIG. 10 is a partial perspective view of another embodiment of thecorrection device, showing the essential portions thereof;

FIG. 11 is a plan view corresponding to FIG. 10;

FIG. 12 is a sectional view taken along the line XII- XII ofFlG. 11;

FIG. 13 is a perspective view of still another embodiment of thecorrection device, showing the essential portions thereof;

FIG. 14 is a front elevation view of the correction device shown in FIG.13;

FIGS. 15, 16, 17 and 18 are perspective views of other embodiments of acorrection device in accordance with the invention, showing theessential portions thereof;

FIG. 19 is a sectional view of a further embodiment of the correctiondevice, again showing the essential portions thereof;

FIG. 20 is a perspective view, partly broken away, of another embodimentof the correction device in accordance with the invention, showing theessential portions thereof;

FIG. 21 is a sectional view of an embodiment of the invention in whichthe belt roller is supported by an automatic self-aligning bearing;

FIG. 22 is a perspective view of another embodiment of the inventionbelt deflection correction device;

FIG. 23 is a fragmentary front elevation view illustrating the manner inwhich one side edge of a deviated very wide belt comes into engagementwith the corresponding belt deflection detection roller, in the deviceof FIG. 22;

FIG. 24 is a perspective view illustrating one form of support means forswingably supporting a belt roller;

FIGS. 25a, 25b and 250 are partial end elevation views showing therelative positions, in operation, of belt deflection detection rollersand belt roller push-out members of the device shown in FIG. 22;

FIGS. 26a and 26b are end elevation views illustrating one embodiment ofbraking means for the belt deflection detection rollers;

FIG. 27 is a partial plan view corresponding to FIG. 26b;

FIG. 28 is a side elevation view illustrating another embodiment of thebraking means; and

FIG. 29 is a fragmentary side elevation view of yet another embodimentof a belt deflection correction device in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 2 through 5,in the embodiment of the invention therein illustrated, an endless belt1, having a relatively small thickness and a relatively large width, istrained about a pair of belt rollers 2 and 3 oriented substantiallyparallel to each other. Roller 2 is rotatably journalled in bearings 5and 6 secured to a base plate 4, and a pulley 8, on an endof shaft 7supporting roller 2, is driven by an electric motor (not shown) forrotating roller 2 so as to move endless belt 1 in the direction of arrowa, illustrated in FIG. 5. The other roller 3 is journalled in bearings9a and 9b formed by bending opposite ends of a swinging member 9. Apivot shaft 10 is fixed centrally to swinging member 9 and is looselysupported in a bearing 11 on base plate 4.

A helical spring 13 embraces pivot shaft 10 between a disk or washer 12,secured to shaft 10 at its outer end, and bearing 11, so that member 9is biased by spring 12 to move in a direction in which it pulls andtensions belt 1. The tension of endless belt 1 can be suitably adjustedby varying the resilience of spring 13 by adjusting a nut 14 threadedlymounted on the outer end of shaft 10, to move disk 12 along shaft 10.

A stop is formed by a flange bent out from the lower side edge of member9 between pivot shaft 10 and bearing 9a, and this stop is biased by aspring 15, shown in FIG. 5, to press against the top end of a threadedrod 16. Rod 16 has its lower end portion formed with an external thread16a which is engaged in an internally threaded member 18 secured to theforward end of a lower support arm 17, as shown in FIG. 3. The upper endportion of rod 16 extends loosely through an opening formed in theforward end portion of an upper supporting arm 19. Support arms 17 and19 have their base ends interconnected by two screws 20 and 21 extendingthrough respective slots 22 and 23 in base plate 4, so that plate 4 ispositioned between arms 17 and 19. Thus, arms 17 and 19 can be adjustedalong slots 22 and 23 and, by varying the positions at which arms 17 and19 are mounted on plate 4, it is possible to vary the position ofcontact between rod 16 and stop 9c so as to thereby vary the angle ofswinging of member 9 with respect to the amount of actual displacementof rod 16 when this rod is moved upwardly and downwardly as describedhereinafter.

A rotation-transmission belt 24 is trained about a pulley 25, rotatablymounted between support arm 19 and base plate 4, and pulleys 26 and 27rotatably mounted on base plate 4 through the medium of respective pins30 and 31. A frusto-conical detection roller 28 is fixed on pulley 26,and a similar detection roller 29 is fixed on pulley 27. These detectionrollers are so disposed that their conical surfaces are spaced slightlyapart from respective opposite side edges of endless belt 1. Statedanother way, the conical surfaces of the two detection rollers arespaced apart a distance which is somewhat greater than the width ofendless belt 1. Thus, when endless belt 1 moves along a normal path ofmovement between the detection rollers 28 and 29, the opposite sideedges of the belt do not engage these detection rollers.

However, if belt 1, moving in the direction of arrow a in FIG. 5deviates from its normal path of movement in the direction of arrow b, aside edge la of belt 1 will engage the conical surface of detectionroller 28 and frictionally effect rotation of roller 28 in the directionof the arrow indicated thereon. The rotation of detection roller 28 istransmitted to pulley through belt 24 so as to rotate threaded rod 16.Thread 16a has a direction such that, when rod 16a is rotated bydetection roller 28, the rod is moved upwardly. Thus, when belt 1deviates toward detection roller 28, the upper end of rod 16 moves stop90 of member 9 upwardly so that member 9 is tilted against the bias ofspring 15. Thereby, that end portion 3a of the supporting shaft of beltroller 3 disposed toward that side edge of belt 1 facing the directionof deflection is moved upwardly. As end portion 3a is moved upwardly,belt 1 begins to shift in a direction opposite to arrow b, therebydisengaging side edge la of belt 1 from detection roller 28 and, at thesame time, arresting the movement of threaded rod 16.

If further shifting of belt 1 in a direction opposite to arrow b bringsthe other side edge lb of belt 1 into engagement with detection roller29, the latter is rotated in the direction of the arrow thereon so thatpulley 25 is rotated in a direction opposite to the arrow thereon andthreaded rod 16 accordingly is moved downwardly. Consequently, member 9is moved downwardly by spring 15, and end portion 3a of the supportingshaft of belt roller 3 is moved downwardly, thereby tilting belt roller3 in a direction such that endless belt 1 shifts again in a direction ofarrow b. It will be appreciated that the mounting member 9, pivoted bypivot shaft 10, oscillates under instructions" from detecting rollers 28and 29 to automatically and continuously correct deflection of endlessbelt 1 in either direction from its normal path of movement.

The described embodiment of the correction device is effective tocorrect deflection or deviation of endless belt 1 when its direction ofmovement is reversed so that it moves in a direction opposite to arrowa. In this case, the end portion of the supporting shaft of roller 3nearer to that side edge 1a of belt 1 coming into contact with thedetection roller, is moved downwardly and belt 1 shifts toward thehigher portion of roller 3 which is consequently tilted.

By reducing as much as possible the frictional drag between thedetection roller and the supporting shaft, as by using antifrictionbearings and reducing the pitch of thread 16a of rod 16, it is possibleto set member 9 smoothly in motion while endless belt 1 engages thedetection rollers and drives the same with a small force.

It will be understood that the objective can be accomplished by usingcylindrical detection rollers in place of the frusto-conical detectionrollers described above. However, it will be seen that the surfaces ofdetection rollers which come into engagement with side edges of theendless belt preferably are conical in shape to attain optimumengagement between the side edges of the belt and the detection rollers,since the conical surfaces of the detection rollers :are compatible withthe side edges of the belt as shown in FIG. 4 in dotted lines at la.

While the embodiment of the invention shown in FIGS. 2 through 5utilizes an endless rotation-transmission belt, a linkage may besubstituted for belt 24. Such a linkage arrangement, operating; as arotation-transmission mechanism, is illustrated in FIGS. 6 and 9. InFIG. 6, a ring 41a is formed at the base end of a connecting rod 41, andfits loosely over an eccentric cylindrical member 43 fixed to orintegral with the lower portion of a detection roller 42. A feed pawl44, having arms 44a and 44b projecting in opposite directions, ispivotally connected, through the medium of a pin 45, to the forward endof connecting rod 41. The lower end of pin 45 is loosely received in aslot 47 formed in base plate 4, so that movement of connecting rod 41 isregulated by the cooperation between pin 45 and slot 47. The forward endof feed pawl 44 is spring biased, by a spring which has not been shown,to press against serrations of the outer periphery of a wheel 48 securedto threaded rod 16.

If side edge lb of belt 1 comes into engagement with detection roller42, as viewed in FIG. 7, to rotate the detection roller, connecting rod41 moves in crank motion to cause feed pawl 44, at its forward end, torotate wheel 48 intermittently in the direction of the arrow, as shownin FIG. 6. The amount of eccentricity of cylindrical member 43 is suchthat wheel 48 is moved through a distance greater than the dimension ofone tooth of the serration on its outer periphery as a result of onereciprocating movement of feed pawl 44. Arm 44a is arranged to abutagainst a pin 50 a little before pin 45 projects and reaches one limitof its range of movement. If pin 45 moves further in slot 47 thereafter,then feed pawl 44 pivots clockwise about pin 45 while arm 44a ismaintained in contact with pin 50, so that feed pawl 44 is released fromengagement with wheel 48.

A mechanism 52 similar to that just described is provided on the rightside of wheel 48, and is arranged to rotate wheel 48 in a directionopposite to the arrow. A feed pawl 53 of mechanism 52 is disposed inspaced relation to wheel 48. Feed pawl 53 is adapted to pivotcounterclockwise about a pin 56 when the latter reaches one limit of itsrange of movement and an arm of feed pawl 53 abuts a pin 55.

On the other hand, if pin 45 is pulled back to its other limit ofmovement in slot 47, feed pawl 44 pivots clockwise about pin 45 when arm44b abuts against a pin 51, so that feed pawl 44 is released fromengagement with wheel 48. Thus, when pin 45 reaches either of its twolimits of movement in slot 47, or when connecting rod 41 is brought to adead center position, feed pawl 44 is released from engagement withwheel 48 so that one feed pawl 44 inhibits the rotation of wheel 48 whenthe other feed pawl 53 is operative, and vice versa.

When connecting rod 41 is not in its dead center position, or when pin45 remains stationary in an intermediate position in its range ofmovement, feed pawl 44 remains in engagement with wheel 48. When this isthe case, if the other feed pawl 53 is rendered operative and rotateswheel 48 in a direction opposite to the direction of the arrow, then theserration of wheel 48 pushes and moves feed pawl 44 and causes eccentriccylindrical member 43 to rotate about a shaft 57 while connecting rod 41is moved to a limit of this range of movement. This causes feed pawl 44,which has been maintained in engagement with wheel 48, to be releasedfrom such engagement so that wheel 48 can rotate freely without anyinterruption. Pins 50, 51 and 55, as well as a pin 58 functioning in thesame manner as pin 51, are all secured to base plate 46.

FIG. 8 illustrates the linkage, serving as a rotationtransmissionmechanism, in which a shaft 62, supporting a detection roller 61, isdisposed parallel to the belt supporting rollers. A lever 64 ispivotally supported by a pin 63 on the base plate, and has one end bentupwardly and formed with an elongated notch 65 loosely receiving thereinan eccentric pin on the inner end of detection roller 61 and extendingparallel to shaft 62. Accordingly, if detection roller 61 is rotated,lever 64 will oscillate and cause a feed pawl 66, pivotally mounted onthe opposite end of lever 64 by a pin 67, to rotate wheel 48intermittently in the direction of the arrow. Pins 69 and 70 on baseplate 4 correspond to pins 50 and 51 of FIG. 6, and act on feed pawl 68in the same manner, so that explanation of the action of these pins isbelieved not necessary.

The movement of lever 64 in FIG. 8 is limited by pin 63 and eccentricpin 66, so that a guide slot, such as the slot 47 of FIG. 6, is notnecessary. It will be understood that another mechanism, similar to themechanism 71 shown in FIG. 8, is provided on the right side of wheel 48as shown in FIG. 8.

It is possible to swing the member supporting belt roller 3 even if thepulley 25 of FIG. 2 is omitted, and such an arrangement is shown in FIG.10. Referring to FIGS. l0, l1 and 12, detection rollers 73 and 74,arranged at adjacent opposite side edges of belt 1, are connected toeach other by an endless belt 75. One detection roller 73 is secured toa rod 76 having a threaded portion 76a threadedly engaged in aninternally threaded member 77 on base plate 4, and the other detectionroller 74 is rotatably mounted on a shaft 78 secured to base plate 4.With this arrangement, rod 76 is moved upwardly or downwardly wheneither detection roller 73 or 74 is driven by endless belt 1. Thus, if astop 72a of member 72 supporting belt roller 3 is caused to pressagainst the upper end of threaded rod 76 by the bias of a spring 79, theaxial vertical reciprocation of threaded rod 76 can be translated intoswinging of member 72. Member 72 may be pivotally connected to baseplate 4 by the same means as illustrated for member 9 shown in FIG. 3.

FIGS. 13 and 14 illustrate an embodiment of the invention wherein therotation of detection rollers 82 or 83 is transmitted to a threadedshaft 81, disposed parallel to the belt supporting rollers, which inturn displaces a movable cam member 84 threadedly engaged with a thread81a of shaft 81, and having a cam surface 84a. Cam member 84 is movedparallel to shaft 81 so that a roller 85, pressing against cam surface840, is moved upwardly and downwardly thereby imparting a swingingmovement to member 86 which supports a belt supporting roller. A shaft88 having detection roller 82 secured to its upper end is interconnectedwith shaft 81 by helical gears 89 and 90 on respective shafts 88and 81and a shaft 91 carrying a detection roller 83 is interconnected withshaft 81 by helical gears 92 and 93. Cam member 84 is suitably supportedfor movement by threaded shaft 81 which is journalled by a bearing (notshown) secured by base plate 4.

FIG. 15 illustrates an embodiment of the belt correction deflectiondevice in which detection rollers 94 and 95 are supported by respectivehorizontally oriented shafts. Referring to FIG. 15, the detectionrollers are rotatably supported by a base plate (not shown) and a gear96, fixed to or integral with detection roller 94, transmits rotation ofroller 94 through an intermediate gear 97 to a gear 99 secured to oneend of a threaded shaft 98. A gear 100, fixed to or integral withdetection roller 95, meshes directly with a gear secured on the otherend of shaft 98. Thus, the direction in which threaded shaft 98 rotates,when roller 94 is driven by the endless belt moving in the direction ofarrow a, is opposite to the direction in which shaft 98 rotates whendetection roller 94 is driven byendless belt 1. Thus, it is possible toaxially reciprocate a movable member 111 threadedly engaged with athread 98a of shaft 98. Member 111 is secured to a shaft 112 mounting,at its forward end, a roller 113 pressing against a cam edge 114a on theunderside of member 114 which supports an endless belt supportingroller. Member 114 may be pivoted, by a pivot shaft, on the base platein the same manner as the member 9 shown in FIG. 5.

In the embodiment of the correction 'device shown in FIG. 16, onedetection roller 116 is cooperable with a side edge 1a of the lower runof belt 1, and the other detection roller 117 is cooperable with a sideedge 1c 7 of the upper run of belt 1. A pulley 118, fixed to or integralwith detection roller 117, is connected by an endless belt 121 to apulley secured to one end ofa threaded shaft 119, and detection roller116 is secured to the opposite end of shaft 119. Shaft 119 has a thread119a threadedly engaged with a movable member 122. Movable member 122 isprovided with a cam member corresponding to the cam 84 of FIG. 13, orthe roller 113 of FIG. 15, for imparting a swinging movement to one ofthe belt roller supporting members.

Referring now to the embodiment of the invention shown in FIG. 17,detection rollers and 126 are mounted on the outer ends of respectiveshafts 123 and 124, oriented parallel to the supporting rollers (notshown) for endless belt 1, and respective gears 127 and 128 are fixed onthe inner ends of the shafts. Gears 127 and 128 mesh with a ring-typeface gear 129 to transmit a swinging movement to a roller supportingmember 131 through the medium of a cam 129a, formed on the underside ofgear 129, and a lever 130. Detection rollers 125 and 126 are rotatablysupported by suitable bearings (not shown) secured on the base plate ofthe apparatus. If either detection roller is driven by a side edge 1a or1b of endless belt 1, then the associated gear 127 or 128 causes gear129 to rotate either clockwise or counterclockwise, and the rotation ofgear 129,

through cam 129a, causes lever 130 to swing about a pivot shaft 132 sothat its forward end 1300 imparts a swinging movement to member 131.Gear 129 may be suitably supported by a vertical shaft (not shown)connected to the base plate. Lever 130 is biased by a spring 133 topivot counterclockwise about pivot shaft 132, so that a pin 134 securedto an end of lever 130 presses against cam 129a.

In FIG. 18, pinions 137 and 138 fixed to or integral with respectivedetection rollers and 136 mesh with a gear 139, so that rotation ofeither detection roller is transmitted to gear 139. A swinging movementis imparted to a swinging member 141 pressing against a cam on the uppersurface of gear 139. Gear 139 is rotatably supported by a shaft 142secured to the base plate of the apparatus.

In FIG. 19, detection rollers 145 and 146, supported by horizontalshafts rotatably supported on the base plate, are fixed to or integralwith respective gears 147 and 148 meshing with a face gear 144 having,on its upper surface, a cam 143 similar to the cam 140 shown in FIG. 18.1

In all of the embodiments described above, the detection rollers aredisposed between a pair of belt supporting rollers, such as the rollers2 and 3 of FIG. 2. However, the detection rollers may be rotatablymounted on the shaft supporting one belt roller, as shown in FIG. 20.Referring to FIG. 20, one belt roller 152, for an endless belt 151, issupported by a shaft 153 mounted in suitable bearings secured to a baseplate (not shown). A detection roller 154 is rotatably mounted on shaft153 adjacent one end of roller 152, and a detection roller 155 isrotatably mounted on shaft 153 adjacent the opposite end of roller 152.Both detection rollers, 154 and 155, are freely rotatable on shaft 153.The other belt roller 156supporting belt 151 is rotatably supported by aswinging member 157 supported on a pivot shaft 158 in the same manner asdescribe in connection with FIG. 2.

A roller 159, rotatably supported on a pin or the like connected to thelower edge of member 157, is biased by a spring 162 connected to member157 to press against a cam surface a on the upper surface of movable cammember 160. Member 160 is threadedly engaged with a thread 163a of athreaded shaft 163 which has pulleys 164 and 165 secured to itsrespective opposite ends. Pulley 164 is connected to a pulley portion ofdetection roller 154 by a cross belt 166, and pulley 165 is connected toa pulley portion of detection roller 155 by an open endless belt 167.

Assuming that endless belt 151, moving in the direction of the arrow, isdeflected from its normal path of movement toward detection roller 154,so that the inner side edge 151a of belt 151 rides on roller 154, thisroller will be driven by belt 151 and its rotation will be transmittedto pulley 164 through cross belt 166, so that shaft 163 'is rotated inone direction. Thread 163a of shaft 163 is so formed that, whendetection roller 154 is driven by endless belt 151, member 160 moves inthe direction of the arrow therebeneath. Consequently, when belt 151 isdeflected toward roller 154, correction of the belt deflectioniseffected by moving roller 159 upwardly by cam surface 160a. On theother hand, as detection roller 155 and pulley 165 are interconnected bybelt 167, shaft 163 is rotated in the reverse direction when detectionroller 155 is driven by endless belt 151, thereby moving member 160 inthe direction opposite to the direction of the arrow. Thus,- deflectionof belt 151 toward detection roller 155 is 5 corrected.

It will be understood that the diameter of the detection rollers may bemade slightly larger than that of belt roller 152, that the detectionrollers may have a frustoconical shape, or that the outer peripheralsurfaces of the detection rollers may be knurled, in order to assurethat endless belt 151 is brought into positive engagement with arespective detection rollers upon deflection from its normal path ofmovement.

In the embodiments hitherto described, the swingable belt roller issupported by a swinging support. However, if a belt roller is supportedby an automatic self-aligning bearing 171, as shown in FIG. 21, theswinging support may be omitted. Bearing 171 includes an inner racesecured to a shaft 174 in turn secured to stationary side plates 172 and173 at opposite ends thereof. Furthermore, bearing 171 includes an otherrace firmly fixed within belt roller I170.

Rollers 175 and 176, pressing against opposite ends of roller 170 frombelow, are supported by pivots on the respective opposite ends of aswingable member 177. Member 177 is pivoted on a stationary member by ashaft 178 at its mid portion, and has a portion disposed between pivotshaft 178 and roller 175 which is biased by a spring to press againstthe top end of a vertically reciprocable shaft 179 which is adapted tobe axially reciprocated by two detection rollers. By moving shaft 179upwardly and downwardly, a swinging movement is imparted to belt roller170.

In the embodiment of the invention shown in FIG. 22, side plates 202 and203 are secured to a bottom plate 201, and shafts 204a and 2050 arerotatably supported by the lower portions of the side plates androtatably support belt rollers 204 and 205. Pins 206 and 207 extendthrough the upper portions of respec hanger 212 is loosely supported bya pin 212a secured to the other end of lever 208, and another hanger 213is loosely supported by a pin 213a secured to the other end of lever209. A belt roller 214 is supported by hangers 212 and 213 through themedium of a shaft 214a having its opposite ends extending through thesehangers. Levers 208 and 209 are biased by springs 210 and 211 to pivotclockwise, as viewed in FIG. 2, about respective pins 206 and 207, sothat belt roller 214 is urged to move upwardly. An endless belt 215,having a relatively large width, is trained'around belt rollers 204, 205and 214, and tensioned by belt roller 214.

Shaft 214a of belt roller 214 has its opposite ends loosely received incutouts 216a and 21Gb formed in opposed rising portions of a supportingmember 216, shown more clearly in FIG. 24, which is swingably supportedsubstantially at its central portion by a pivot shaft 217 secured to asupport 218. Support218 is secured to a shaft 219 having its oppositeends secured to side plates 202 and 203, so that belt roller 214 canswing in the direction in which belt 215 is deflected in order torestore belt 215 to its normal path of movement.

A gear 220 is secured to one end of shaft 204a supporting belt roller204, and is driven by drive means (not shown) to rotate in the directionof arrow e. Belt roller 204 thus rotates in the direction of arrow etogether with gear 20, so as to move belt 215 in the direction ofarrowf.

Belt deflection detection rollers 221 and 222 are rotatably mounted atthe upper portions of respective side plates 202 and 203 through themedium of respective shafts 223 and 224, and are disposed on oppositesides of belt 215 near belt roller 214. Detection rollers 221 and 222are spaced axially from each other a distance slightly greater than thewidth of endless belt 215. Rollers 221 and 222 are formed, at portionsthereof corresponding to side edges of belt 215, with respectivefrustoconical surfaces 221a and 222a, with which the side edges of belt215 are adapted to come into engagement when belt 215 is deflected fromits normal path of movement.

Respective belt roller push-back members 225 and 226 protrude radiallyfrom the cylindrical portions of detection rollers 221 and 222, and arefixed to the associated detection roller or formed integrally therewith.If belt 215 is deflected from its normal path of movement and broughtinto engagement, at its side edge, with either frusto-conical surface221a of roller 221 or frusto-conical surface 222a of roller 222, so thateither roller 221 or 222 is driven by belt 215, belt roller push-backmembers 225 and 226 will rotate with the respective rollers 221 and 222and push backwardly the corresponding ends of belt roller 214. FIG. 23shows belt 215 deflected toward side plate 203 and driving, by its sideedge, frusto-conical surface 222a of detection roller 222.

Let it be assumed that belt roller 214 is disposed in a tilted positionin FIG. 22, and in which its one end portion 214c is moved forwardly, inthe direction of movement of belt 215 at the top of roller 214, or inwhich the other end portion 214b is disposed nearer than normal todetection roller 221, so that belt 215 moving on belt roller 214 isdeflected toward side plate 202. In such case, endless belt 215, movingin the direction of arrow f, will soon begin to engage, at its side edgetoward plate 202, the frusto-conical surface 2210 of belt deflectiondetection roller 221, as shown in FIG. 25a, and cause roller 221 torotate in the direction of arrow g. At first, roller 221 rotates lightlyin the direction of arrow g as the side edge of belt 215 comes intoengagement with frusto-conical surface 221a. However, when belt rollerpush-back member 225 comes into contact with an end portion 214]; ofroller 214, as shown in FIG. 25b, the frictional drag between roller 214and member 225 causes member 225 to rotate at high speed, so that roller221 also rotates at high speed in the same direction. Thus, end portion214!) of belt roller 214 is pushed and moved by push-back member 225, sothat belt roller 214 swings about supporting shaft 217 (FIG. 24), withsupporting member 216, and shifts in a direction in which the endportion 214b moves away from roller 221, or in the direction of thearrow h in FIG. 250. The swinging and shifting movements of the beltroller 214 causes the end portion 214c of the roller 214 on the side ofthe side plate 203, shown in FIG. 22, to move toward the belt deflectiondetection roller 222. Thus, the belt 215 begins to move away from thedetection roller 221 to the right in FIG. 22. If the side edge of belt215 toward side plate 203 begins to drive detection roller 222, the sameoperation will be performed and belt roller 214 will begin to cause itsend portion 214b to move toward roller 221. This cycle of operation isrepeated during movement of endless belt 215, so that the deflection ofbelt 215 from its normal path of movement is corrected and the belt canmove without deflection from its normal path.

Belt deflection detection rollers 221 and 222 begin to rotateimmediately as soon as they come into engagement with belt 215, somatter how small the force with which belt 225 and 226 into abuttingengagement with belt roller 214. The push-back members push back beltroller 214 by cooperation between these members and belt roller 214. Theforce with which belt 215 rubs against rollers 221 and 222 does not haveany direct relation in the action of moving back belt roller 214. Afterbelt roller 214 is swung, and shifted in position, by either push-outmember 225 or push-out member 226, belt 215 immediately begins todeviate in the opposite direction, so that the belt does not remain longin rubbing engagement with either roller 225 or 226. Thus, thisarrangement causes less wear and tear on the side edges of the very wideendless belt 215 than is caused by conventional correction devices.

In FIG. 22, resilient support members 227, only one of which is shown,are mounted on side plates 202 and 203 at positions below the beltdeflection detection rollers 221 and 222. A respective brake member issecured to the free end of each support plate and is adapted to beurged, by the resilient force of the associated plate 227, to pressagainst the peripheral surface of the roller 221 or 222. Brake members228 are intended to control the belt deflection detection rollers 221and 222 so that, after the belt roller 214 is moved by the push-backmembers 225 and 226, rollers 221 and 222 are prevented from continuingto rotate inertia or the like, and are simultaneously brought topositions in which they push against the belt roller.

The provision of brake members 227 is effective to assure that the beltdeflection rollers 221 and 222 are halted in good positions at alltimes, after moving back roller 214, no matter how high the speed ofendless belt 215. The arrangement is also effective to prevent beltroller'214 from being repeatedly pushed back by members 225 and 226.

FIGS. 26a and 26b illustrate another brake means for detection rollers221 and 222. In these figures, the brake means comprises brake belts 229each secured at one end to the underside of a support 216 and, at theother end, to a fixed member S (only one brake belt being shown). Withthis brake means, belt deflection detection roller 222 can becontrolled, when driven to rotate by the deflected endless belt 215, andbelt roller 214 is pushed by belt roller push-out member 226 as shown inFIG. 26b, by brake belt 229 which is tensioned as belt roller 214 ismoved backwardly. Thus, rollers 221 and 222 can be brought to very goodpositions after belt roller 214 is moved backwardly, thereby permittingcorrection of the deflection of the endless belt 215 more accurately andsmoothly. Furthermore,

as no brake is applied to rollers 221 and 222 when belt deflection isinitially detected, rollers 221 and 222 can be driven by belt 215 withonly a small force, thus eliminating the danger of damaging the sideedges of belt 215. FIG. 27 illustrates a partial plan view of thearrangement shown in FIGS. 26a and 26b.

Another example of a brake means is illustrated in FIG. 28 as comprisingplate-like brake members 317, each having a brake 317a and secured tothe underside of a support 316. Each brake member 317 functions in themanner such that, when support member 316 moves to a dash-and-dot lineposition 316A, as belt deflection roller 222 is driven by belt 215 torotate and belt roller 214 is pushed by push-back member 226 into adash-and-dot line position 214A, brake 317a of brake member 317, whichmoves to a dash-and-dot line position 317a in slaved relation to supportmember 316, restrains push-out member 226. This causes member 226 tostop in a dash-and-dot line position 226A after member 226 has movedbelt roller 214 backwardly. Thus, this brake means also can bring beltroller push-out members 225 and 226 to good positions.

While brake belts 229 and brake members 317 have been described as beingactuated directly as a result of the swinging and shifting in theposition of belt roller 214, it is to be understood that the brakeelements may be actuated indirectly, through a linkage or the like.

The belt roller push-back members described above have been formedcoaxially and integrally with the belt deflection detection rollers, butthe invention is not limited to this form of push-back members and thepush-back members may be formed separately from the detection rollers asshown in FIG. 29. In FIG. 29, a large width endless belt 381, trainedabout a fixed driving belt roller 382 and a swingably supported beltroller 383, moves in the direction of the arrow 1'. A belt deflectiondetection roller 384 is disposed along the path of movement of belt 381and connected, through an endless belt 385, to a belt roller push-backmember 386 disposed above belt roller 383. Only one detection roller 384is illustrated, but a second roller, similar in function and operation,is provided on the opposite side of the belt.

If belt 318 is deflected from its normal path of movement and moves intoengagement with detection roller 384 for driving the same in thedirection of the arrow j, push-back member 386 will be moved,simultaneously, in the direction of the arrow k, and belt roller 383will move its end toward push-out member 386 nearer to this member.Accordingly, push-out member 386 pushes the end of belt roller 383, byits projecting pushout portion 386a, and moves belt roller 383backwardly so as to cause belt 381 to shift in a correcting direction.In this way, the deflection of the wide endless belt can be prevented.In this embodiment, also, suitable brake means may be provided to applya brake to deflection detection roller 384 or push-back member 386.

The belt deflection correction devices shown in FIGS. 22 and 29 are verysimple in construction, and permit effecting swinging of the belt rollerby the cooperative action ofthe push-back members and the belt rolleritself. With this arrangement, the belt deflection detecting rollers canbe driven by the wide endless belt with a very small force, so that lesswear and tear is caused to the side edges of the belt and better andmore accurate correction of belt deflection can be attained than ispossible with conventional devices.

In the embodiments of the invention as described above, the wide endlessbelt is trained about two or three belt rollers. It is to be understood,however, that the invention is not limited to these particular numbersof belt rollers, and any suitable number of belt rollers may be used. Ifan exposure device is provided between belt rollers 204 and 205, in theembodiment of FIG. 22, this can constitute an exposure section of acopying machine.

While specific embodiments oil the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be unt derstood that the invention may beembodied otherwise without departing from such principles.

What is claimed is;

l. A belt deflection correction device for a very wide endless belttrained over at least a pair of rollers, at least one of which iscoupled to belt driving means, said device comprising, in combination,means mounting one of said rollers for swinging about a stationary pivotaxis perpendicular to its axis of rotation; a pair of belt deflectiondetecting rollers rotatably mounted on immobile axes adjacent oppositeside edges of said belt and spaced apart a distance slightly greaterthan the width of said belt so as normally to be out of engagement withthe side edges of said belt; and means operatively connecting saiddetecting rollers to said one roller and operable, responsive solely torotation of a detecting roller by engagement with a belt side edge as aresult of belt deflection, to swing said one roller about said pivotaxis in a direction to correct the belt deflection.

2. A belt deflection correction device, as claimed in claim 1, in whichsaid means mounting one of said rollers comprises a bracket rotatablysupporting said one roller and mounted for swinging about said pivotaxis;

said connecting means connecting said detecting rollers to said bracket.

3. A belt deflection correction device, as claimed in claim 1, in whichsaid means mounting one of said rollers comprises a shaft extendingthrough said one roller; and a spherical antifriction bearing engagedbetween a mid portion of said shaft and a mid portion of said roller;said connecting means comprises a swingably mounted bracket having meansat its opposite ends engaged with opposite ends of said one roller.

4. A belt deflection correction device, as claimed in claim 1, in whichsaid connecting means comprises respective belt roller push-back.members rotatable with said belt deflection detecting rollers andoperable, responsive to rotation of the associated detecting roller byengagement with a belt side edge, to engage said one belt-supportingroller to swing the latter about said pivot axis in a direction tocorrect the belt deflection.

5. A belt deflection correction device, as claimed in claim 4, includingrespective brake means each operatively associated with a beltdeflection detecting roller.

6. A belt deflection correction device, as claimed in claim 5, in whicheach brake means is directly engageable with the associated deflectiondetecting roller.

7. A belt deflection correction device, as claimed in claim 6, in whicheach brake means comprises a brake band secured at one end to a fixedpoint and at the opposite end to the adjacent end of a roller supportingbracket constituting said mounting means; each brake band beingtensioned, to engage the associated deflection detecting roller,responsive to engagement of the associated push-back member with saidone belt supporting roller to swing the latter about said pivot axis ina direction to correct the belt deflection.

8. A belt deflection correction device, as claimed in claim 5, in whicheach brake means comprises a brake member secured to the adjacent end ofa bracket supporting said one roller and swingable about said pivotaxis; each brake member responsive to engagement of the associatedpush-back member with said one beltsupporting roller, to swing said oneroller about said pivot axis, being moved to a position in which an endabutment thereof is in the path of movement of the associated push-backmember.

claim 4, in which each belt roller push-back member is positionedadjacent said one belt-supporting roller and is rotatable about an axisspaced from the axis of rotation of the associated belt deflectiondetecting roller; and belt and pulley means interconnecting each beltdeflection detecting roller to the associated push-back member.

10. A belt deflection correction device, as claimed in claim 1,including an axle fixed to rotate with said roller coupled to beltdriving means; said belt deflection detecting rollers being mounted forfree rotation on said axle each adjacent a respective opposite end ofsaid roller coupled to belt driving means; said connecting meansincluding transmission means connecting each belt deflection detectingroller to operating means engageable with said mounting means.

1. A belt deflection correction device for a very wide endless belttrained over at least a pair of rollers, at least one of which iscoupled to belt driving means, said device comprising, in combination,means mounting one of said rollers for swinging about a stationary pivotaxis perpendicular to its axis of rotation; a pair of belt deflectiondetecting rollers rotatably mounted on immobile axes adjacent oppositeside edges of said belt and spaced apart a distance slightly greaterthan the width of said belt so as normally to be out of engagement withthe side edges of said belt; and means operatively connecting saiddetecting rollers to said one roller and operable, responsive solely torotation of a detecting roller by engagement with a belt side edge as aresult of belt deflection, to swing said one roller about said pivotaxis in a direction to correct the belt deflection.
 1. A belt deflectioncorrection device for a very wide endless belt trained over at least apair of rollers, at least one of which is coupled to belt driving means,said device comprising, in combination, means mounting one of saidrollers for swinging about a stationary pivot axis perpendicular to itsaxis of rotation; a pair of belt deflection detecting rollers rotatablymounted on immobile axes adjacent opposite side edges of said belt andspaced apart a distance slightly greater than the width of said belt soas normally to be out of engagement with the side edges of said belt;and means operatively connecting said detecting rollers to said oneroller and operable, responsive solely to rotation of a detecting rollerby engagement with a belt side edge as a result of belt deflection, toswing said one roller about said pivot axis in a direction to correctthe belt deflection.
 2. A belt deflection correction device, as claimedin claim 1, in which said means mounting one of said rollers comprises abracket rotatably supporting said one roller and mounted for swingingabout said pivot axis; said connecting means connecting said detectingrollers to said bracket.
 3. A belt deflection correction device, asclaimed in claim 1, in which said means mounting one of said rollerscomprises a shaft extending through said one roller; and a sphericalantifriction bearing engaged between a mid portion of said shaft and amid portion of said roller; said connecting means comprises a swingablymounted bracket having means at its opposite ends engaged with oppositeends of said one roller.
 4. A belt deflection correction device, asclaimed in claim 1, in which said connecting means comprises respectivebelt roller push-back members rotatable with said belt deflectiondetecting rollers and operable, responsive to rotation of the associateddetecting roller by engagement with a belt side edge, to engage said onebelt-supporting roller to swing the latter about said pivot axis in adirection to correct the belt deflection.
 5. A belt deflectioncorrection device, as claimed in claim 4, including respective brakemeans each operatively associated with a belt deflection detectingroller.
 6. A belt deflection correction device, as claimed in claim 5,in which each brake means is directly engageable with the associateddeflection detecting roller.
 7. A belt deflection correction device, asclaimed in claim 6, in which each brake means comprises a brake bandsecured at one end to a fixed point and at the opposite end to theadjacent end of a roller supporting bracket constituting said mountingmeans; each brake band being tensioned, to engage the associateddeflection detecting roller, responsive to engagement of the associatedpush-back member with said one belt supporting roller to swing thelatter about said pivot axis in a direction to correct the beltdeflection.
 8. A belt deflection correction device, as claimed in claim5, in which each brake means comprises a brake member secured to theadjacent end of a bracket supporting said one roller and swingable aboutsaid pivot axis; each brake member responsive to engagement of theassociated push-back member with said one belt-supporting roller, toswing said one roller about said pivot axis, being moved to a positionin which an end abutment thereof is in the path of movement of theassociated push-back member.
 9. A belt deflection correction device, asclaimed in claim 4, in which each belt roller push-back member ispositioned adjacent said one belt-supporting roller and is rotatableabout an axis spaced from the axis of rotation of the associated beltdeflection detecting roller; and belt and pulley means interconnectingeach belt deflection detecting roller to the associated push-backmember.